[PATCH] Fix the build for git repositories with multiple remotes.

[Jordan Rose]

  The URL is going to be unusable anyway – it's not just removing the first cfe/ but everything //up to and including// the first cfe/. It might be nice to have Version.cpp do a nice job for the usual git mirrors, but simply including the full repo URL instead of just the branch part isn't going to hurt anyone.

  I agree that it makes sense to use `origin` if it exists; however, there are very few cases where `origin` isn't the first remote anyway. I would just commit this as is.

http://llvm-reviews.chandlerc.com/D1659